Property Improvement of Electrical Insulating Rubbers by Thermal and Radiation Stresses

We gave various kinds of thermal and gamma-ray radiation stresses and their combination to rubber-containing epoxy resin, flame-retardant ethylene propylene diene rubber, and silicone rubber to study the resultant changes in their mechanical, dielectric, and insulating properties. The property change appears significantly differently, depending on what property we pay attention to. For example, mechanically degraded silicone rubber exhibits a much higher electrical resistivity than the original undegraded state. Similar changes in mechanical deterioration and concurrent improvement of insulating properties are observed in the other two materials.